The present invention relates to an apparatus for producing an intensely bright, highly focused beam of light from a conventional incoherent lamp source. More particularly, the invention is directed, to an apparatus which simulates the brightness, chromatic and focal properties of a laser and is particularly suited for certain medical applications as a substitute for a laser.
Lasers are broadly applied in a wide range of scientific, industrial, military and medical applications. Depending on the application, use is made of one or more of the unique characteristics of laser light, such as its monochromatic and coherence properties, great beam intensity, and the ability to focus on a very small area. For most medical treatment applications, brightness and narrow focus of laser light are the properties of primary interest. In such applications, the highly directional collimated laser beam is most important because the energy can be easily collected and focused with intense brightness in a small area. The narrow collimated beam can also be easily launched into a fiber optic system.
However, lasers are expensive to manufacture and use, and certain types of lasers useful in medical applications cannot be used in fiber optic systems. Nevertheless, lasers are broadly used in many medical applications from general surgery to more specialized uses in cardiology, dermatology, otolaryngology and dentistry.
In surgical applications, the high intensity, narrowly focused beam characteristics may be most important and, in most applications, narrow spectral band-width properties are not important. In other more specialized medical applications of lasers, wavelength band selection is particularly important, and this property of certain types of lasers dictates their choice. For example, a tunable dye laser permits wavelength selection required in certain applications. Thus, notwithstanding their current limitations, lasers do provide a broad adaptability to many medical applications for which no suitable alternative apparatus is available.
Conventional lamp-based lighting systems are, of course, also known and widely used in medical applications. However, because of the inability to generate an intensely bright, highly focused beam with a conventional lamp-based system, such systems have generally been relegated to use for illumination or more limited areas of medical treatment not requiring the intensity and collimation which are characteristic of lasers. Conventional lamp-based systems have also utilized fiber optics to enhance the flexibility of illumination systems or to concentrate and improve the intensity of illumination.
U.S. Pat. No. 4,281,366 discloses a medical examination or surgical lighting apparatus in which reflected tungsten lamp light is focused into a fiber optic bundle for transmission to the site to be illuminated. However, the optical fiber bundle is merely a light transmission medium and provides no increase or enhancement in the power density of the light.
U.S. Pat. No. 4,562,832 discloses a medical illumination apparatus in which conventional lamp light is transmitted through a relatively large diameter monofilament optical guide. The guide is enclosed to enhance its internal reflectivity and light transmission efficiency and to minimize losses. This device is, however, simply a light transmission apparatus concerned primarily with transmitting large amounts of light for illumination.
U.S. Pat. No. 4,385,344 describes the optical fiber transmission of reflected lamp light focused directly into the optical fibers. The reflectorconcentrated light is first directed through an optical bandpass filter to produce light for the fiber optic transmission in a range suitable for photo curing dental materials. In addition to the control of the wavelength of the transmitted light, relatively large diameter optical fibers are utilized to maximize the amount of light transmitted.
U.S Pat. Nos. 2,981,826 and 4,411,490 disclose tapered light pipes used to concentrate light, either lamp-based or natural, into more narrowly channeled beams. However, neither of the disclosed devices is directed at creating high power density light or to channeling the concentrated light into small diameter fiber optic cables.